I know this May be an old topic to do a write up for but I feel it is an important one because many of these 550s are still out there and perhaps changing hands to unsuspecting/unknowing buyers. If you recently purchased a 550 fan congratulations but bought a dud! Don't worry though you are not alone (myself included - I knew what I was getting into though), there are many of us out there and there is hope for your 550 to give you years of enjoyment and trouble free miles. You will read horror stories about your 550 and want to sell it the moment you google 550 blown motor. The purpose of this post is to help 550 owners gain reliability from their 550 by modifying it in the places and ways which polaris engineers forgot to. Some modifications are free and some will cost a few bucks but none of them will be as expensive as a new motor. I am no expert but have done much research and untilized the advice of the experts such as northstardave, to compile this list of upgrades. I am not sure how indepth people need the instructions for each step so I figured I will do a brief overview of everything and if anyone wants a step by step or more detail for any of the fixes just post your request to the thread and I will respond. Also I have read the info but don't recall exactly which 550s are the worst, but what if comes down to if you own a 550 fan you should make the changes I list. If any experts notice I missed something or have something to add or correct please feel free to add your .02. The point of this thread is a one stop for all 550 fan fixes, so please add your input. The majority of the issues with the 550 fan stems from it getting too hot resulting in burn downs, via oil issues, lean fuel issues, etc. I will do each step as a separate post so that I don't have to do all this at one time and so that my pics match up with the step. Ok let's begin at this moment I have 8 ideas for you.....
Step 1 - Exhaust Heat sheild ($ TBA )
Part number - Custom made
the fan for cooling the motor sucks the cold air in directly from the exhaust pipe (not too cool...sorry for the pun), so you need a heat sheild to lessen the temp of the air the fan grabs as well as direct the air from the inlet in the hood down to the fan more directly. As far as I know there is no part number for this part, you will have to fab it yourself or go see your local welder and they should be able to make it up pretty easy. The sheild on mine is 3/32" thick aluminum plate, it has no welds just bends, it measures 11" from front to back, and has 3 faces to it. The height of the top vertical face is 3" at the back and 3-5/8" at the front, so it does slope downwards somewhat as to gets closer to the back of the engine compartment. Te second face is horizontal and measures 2-3/4" at the front and 3-1/2" at the back. You will see in the pic that there is a mount bolt at 5-1/2" from the front edge. The lowest face is also vertical and measures 6-1/8" at the front and stays that height until about half way where it then curves up to a point that is 5" down from the top edge of this face. There are 2 bolts on this face at 4-7/8" and 9-3/4" when measured from the front edge. The bolts are approximately 3-1/8" from the top of this face. I hope some of that makes sense without a working drawing. Use the pics I am including to help you out. If it become necessary I can do up a CAD drawing but for now I want to go on with the list.
Step 1 - Exhaust Heat sheild ($ TBA )
Part number - Custom made
the fan for cooling the motor sucks the cold air in directly from the exhaust pipe (not too cool...sorry for the pun), so you need a heat sheild to lessen the temp of the air the fan grabs as well as direct the air from the inlet in the hood down to the fan more directly. As far as I know there is no part number for this part, you will have to fab it yourself or go see your local welder and they should be able to make it up pretty easy. The sheild on mine is 3/32" thick aluminum plate, it has no welds just bends, it measures 11" from front to back, and has 3 faces to it. The height of the top vertical face is 3" at the back and 3-5/8" at the front, so it does slope downwards somewhat as to gets closer to the back of the engine compartment. Te second face is horizontal and measures 2-3/4" at the front and 3-1/2" at the back. You will see in the pic that there is a mount bolt at 5-1/2" from the front edge. The lowest face is also vertical and measures 6-1/8" at the front and stays that height until about half way where it then curves up to a point that is 5" down from the top edge of this face. There are 2 bolts on this face at 4-7/8" and 9-3/4" when measured from the front edge. The bolts are approximately 3-1/8" from the top of this face. I hope some of that makes sense without a working drawing. Use the pics I am including to help you out. If it become necessary I can do up a CAD drawing but for now I want to go on with the list.
